The present invention relates to waterproofing compositions and more particularly to a method of making such compositions from the by-products of pulp and paper mill operations.
In the manufacture of paper products, by-products are produced which are of limited usefulness or which present disposal problems.
One example of such a by-product is primary sludge resulting from pulp or paper mill operations. While the composition of such sludge will vary to some extent depending upon the particular type of operation carried out at the pulp or paper mill, 20% or more of the volume of such sludge is made up of wood fibers. The sludge typically also includes wood fines, bark pieces, wood dust, water, and other materials such as lime, clay, paper fillers and titanium dioxide. Inorganic materials, which may constitute up to half of the sludge, can include nitrogen, phosphorus pentoxide, calcium, aluminum, and small amounts of a number of other naturally-occurring elements.
The principal method of disposing of primary sludge has been by landfill disposal. However, that method of disposal gives rise to a risk that environmentally-harmful materials may be leached from the primary sludge. The sludge itself can have a relatively high mositure content. Even if it does not, improper operation of the landfill, such as improper grading or infrequent application of cover material, can allow rain or ground water to leach materials from the sludge.
The use of the landfill method of operation is undesirable for other reasons. The cost of operating the landfill, including the cost of acquiring suitable land, can be nearly prohibitive. In addition, the costs of hauling the sludge to the landfill can be quite high.
Another example of a by-product from paper and pulp manufacturing operations is tall oil pitch. Tall oil is a resinous by-product from the manufacture of chemical wood pulp. This by-product is used in the manufacture of such products as soaps, coatings and oils. Tall oil pitch is a non-distillable residue left from the fractionation of tall oil. The pitch, which is removed from the base of a stripping tower during a flash distillation step, is a semi-fluid, tar-like material containing most of the higher alcohols and sterols from the original crude tall oil along with rosin and fatty acids. A typical tall oil pitch material may include 12-30% rosin acids and esters, 35-50% fatty acids and esters and 20-35% neutral materials. Tall oil pitch is readily soluble in aliphatic and aromatic hydrocarbons and is compatible with a variety of oils, asphalts and rosins. Typical properties of tall oil pitch are:
______________________________________ Color, Gardner, 5% in benzene 11-18 Acid Number 20-60 Saponification Number 80-135 Specific Gravity @ 25.degree. C. (77.degree. F.) 0.990-1.010 Softening Point 25.degree.-55.degree. C. (77.degree.-131.degree. F.) Flash Point (Open Cup) 260.degree.-271.degree. C. (500.degree.-520.degree. ______________________________________ F.)